A conventional semiconductor device including a module or the like which contains an inverter unit having upper and lower arms is used as an inverter device for driving a drive motor of, for example, an electric vehicle such as an electric car. A semiconductor device having such features as described above is disclosed, for example, in Patent Document 1.
In a configuration of a conventional semiconductor device containing upper and lower arms as described above, in order to ensure an insulation property between the upper arm and the lower arm, insulation between the upper arm as a high-voltage side arm and the lower arm as a low-voltage side arm should be required as a matter of course, and also when two control substrates for the upper arm and the lower arm are provided on the same base, in order to ensure an insulation property between the two control substrates, the substrates should be arranged with an insulation area provided therebetween, which restricts a reduction in size of the two control substrates in a plane direction.